In addition to growing rapidly, Web pages and sites are constantly being removed, or changing their content.  Web sites or pages can change content without changing their domain name addresses or Ip addresses.  Individual Web pages have an average life span of approximately 90 days. 3.  The Amount of Sexually Explicit Material on the Web There is a vast amount of sexually explicit material available via the Internet and the Web.  Sexually explicit material on the Internet is easy to access using any public search engine, such as, for example, Google or AltaVista.  Although much of the sexually explicit material available on the Web is posted on commercial sites that require viewers to pay in order to gain access to the site, a large number of sexually explicit sites may be accessed for free and without providing any registration information.  Most importantly, some Web sites that contain sexually explicit content have innocuous domain names and therefore can be reached accidentally.  A commonly cited example is http://www.whitehouse.com.  Other innocent-sounding URLs that retrieve graphic, sexually explicit depictions include http://www.boys.com, http://www.girls.com, http://www.coffeebeansupply.com, and http://www.BookstoreUSA.com.  Moreover, commercial Web sites that contain sexually explicit material often use a technique of attaching pop-up windows to their sites, which open new windows advertising other sexually explicit sites without any prompting by the user.  This technique makes it difficult for a user quickly to exit all of the pages containing sexually explicit material, whether he or she initially accessed such material intentionally or not.

The percentage of Web pages on the indexed Web containing sexually explicit content is relatively small.  Recent estimates indicate that no more than 1-2% of the content on the Web is pornographic or sexually explicit.  However, the absolute number of Web sites offering free sexually explicit material is extremely large, approximately 100,000 sites. 4.  American Public Libraries The more than 9,000 public libraries in the United States are typically funded (at least in large part) by state or local governments.  They are frequently overseen by a board of directors that is either elected or is appointed by an elected official or a body of elected officials.  We heard testimony from librarians and library board members working in eight public library systems in different communities across the country, some of whom are also plaintiffs in this case.  They hailed from the following library systems:  Fort Vancouver, Washington; Fulton County, Indiana; Greenville, South Carolina; a regional consortium of libraries centered in Madison, Wisconsin; Multnomah County, Oregon; Norfolk, Virginia; Tacoma, Washington; and Westerville, Ohio.  The parties also took depositions from several other librarians and library board members who did not testify during the trial, and submitted a number of other documents regarding individual libraries’ policies. 1.  The Mission of Public Libraries, and Their Reference and Collection Development Practices